ooh, ooh, time division multiplexing. neat stuff.
optical? wow, that's so new it's still in the whoop dee doo, look at my new stuff category around here.
Yeah, we're working on FTTH (Fiber to the Home). It's GPON - Gigabit Passive Optical Network. Each card (a blade that plugs into a larger chassis) has 2 PONs. Each PON can serve 32 customers - so 64 customers per card, and it's possible to have 22 cards in a Chassis.
All 32 customer ONTs (Optical Network Terminator) sit on the PON at the same time behind a 32x passive optical splitter. They all see the same light at the same time. But, to keep them from stepping on each other (all of them flooding the pipe with light at once would be indecipherable), only one is allowed to "talk" at a time. Thus, the optical line has 32 "slots", and each ONT gets to talk during his time - the magic of TDM!
Of course, there is the ever-so-slight possibility of a "Rogue ONT" which is an ONT that has gone bad and turns its laser full on all the time….that brings down the whole PON and the rest of the 31 customers on it. For that reason, some Telcos are nervous about GPON even though it's a proven technology, and rogues are rare.
The answer is Active-E which serves up 24 one-to-one optical connections to 24 ONTs. The connection is optical ethernet, and not TDM since each ONT has it's own personal fiber. That way, if one goes rogue, it's only that one that is affected since the others have their own fibers.
CARP! Look what you made me do!
